I dont think Marty literally thinks $5.
Perhaps he is suggesting that if people currently selling full decal sets at $299, they arent costing them $280 and only making $20.

However,
If you owned a Black Knight 2000 with a shitty cabinet, and u wanted the machine to look brand new, do u think u could go on ebay and buy a full set of cabinet decals for $20 ? ofcourse not. So, if someone did what no-one had done, and now made them available, what do u think would be a resonable cost.?  If i said i will give yu a set for say $50, is that resonable ? If i said $100, is that reasonable, if i said $150 is that resonable and so on.
Its all about supply and demand. But profit is not what is on offer here.

It is about supplying/printing full decal sets that are not currently available anywhere in the world.
Its not about whether they cost 20 cents to make or a million bux. Its about providing decals that no one has/provides.
Its not a money making exercise.Never was, never will be.

The second thing is then about supplying them at a reasonable cost that is accepted everywhere and anywhere as being reasonable.
The various considerations, that affect this, are the quality of materials used, the quality of the printing process and the method of shipping etc.
Obviously, the graphic atrist and other labour/set up costs will be integrated. I note, that highly professional people within the printing industry, do not operate, purchase and maintain millions of dollars of equipment at $20 per hour.

If i walked in to my contacts business and expected him to do the most professional quality job, using the best equipment money can buy, whilst using
the best materials, and expected him to print me full decal sets, and laminated, for $10 or $20 bux a set, i would be dreaming.

The last item, that needs to be taken into consideration, is whether i am having 1 set done , or 100 sets done at a time.etc etc.

Dont worry about the pricing, lets cover the production step, and the quality etc, followed by the "yes, i like what i see, and i want some" bit first.
The pricing will take care of itself. The only people who pay stupid money are fools, and since there are no fools on this forum, i dont think anyone has to be worried about reasonable cost pricing from me.

Also, I am compiling a list of decals that people want to be produced that arent avail. Email me. Like the person who said Terminator 2, i will now add that. If u dont tell me the ones u want me to organise, they wont get done.Lets compile a list first guys. I will do the rest.